The molecular mechanisms of how B. burgdorferi targets connective tissues and causes arthritis is not understood. It has been shown that B. burgdorferi has a predilection for collagenous tissue and can interact with fibronectin and cellular collagens. The spirochetes can bind to a number of different cell types, including fibroblasts. Recently, Bucala et al. (Mol. Med. 1:71) described a circulating fibroblast-like leukocyte called the peripheral blood fibrocyte. These cells, which express collagen types I and III as well as fibronectin, may play a role in wound healing. Fibrocytes also possess the potential to target pathogens to connective tissue. We speculated that binding of B. burgdorferi to this novel class of leukocytes may represent one mechanism by which the spirochete targets to the joint. Recent evidence demonstrats that B. burgdorferi does possess the ability to bind and penetrate both human and monkey (rhesus) fibrocytes in vitro. The potential of this interaction for connective tissue targeting of B. burgdorferi, and potentially other pathogenic organisms, is both intriguing and far reaching. The molecular mechanisms of how B. burgdorferi targets connective tissues and causes arthritis is not understood. It has been shown that B. burgdorferi has a predilection for collagenous tissue and can interact with fibronectin and cellular collagens. The spirochetes can bind to a number of different cell types, including fibroblasts. Recently, Bucala et al. (Mol. Med. 1:71) described a circulating fibroblast-like leukocyte called the peripheral blood fibrocyte. These cells, which express collagen types I and III as well as fibronectin, may play a role in wound healing. Fibrocytes also possess the potential to target pathogens to connective tissue. We speculated that binding of B. burgdorferi to this novel class of leukocytes may represent one mechanism by which the spirochete targets to the joint. Recent evidence demonstrats that B. burgdorferi does possess the ability to bind and penetrate both human and monkey (rhesus) fibrocytes in vitro. The potential of this interaction for connective tissue targeting of B. burgdorferi, and potentially other pathogenic organisms, is both intriguing and far reaching.